Works very well. The mount is secure on both the lens and the body side. I can't detect any play. Machined from aliminum the build quality seems very good. It is not explained in the product description but the biggest feature of this lens adapter compared to other K-NEX adapters is that it provides aperture control. This is important for Pentax K lenses that do not have an aperture ring, for example DA 50mm f1.8. The aperture control is provided through a click-stop shiny ring. It clicks with authority and has perfect damping. You have to count the click stops to determine the aperture value but using the live preview on A6000, I have no problem judging the DOF. Another great feature is the matte black paint inside. Most others use shiny black which causes internal reflections and loss of contrast. Overall, I am very pleased with this adapter.